The former employee faces up to 10 years imprisonment and a $250,000 fine

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Apple CEO Tim Cook speaks during an announcement of new products at the Apple Worldwide Developers Conference Monday, June 4, 2018, in San Jose, Calif.

Buried in a criminal complaint against a former Apple engineer who's being charged with stealing trade secrets is a remarkable revelation about the size of Apple's autonomous car project: 5,000 employees are working on it, CNBC reported.

Xiaolang Zhang, hired by Apple to work on software and hardware for self-driving cars in December 2015, is accused of downloading files with proprietary information during paternity leave, according to a criminal complaint filed in federal court in Santa Clara, California, on Monday.